This invention relates to lubricant greases and to a means for inhibiting their corrosiveness. In a more particular aspect, this invention concerns itself with perfluorinated polyether grease compositions and to the use of silicone fluids for inhibiting their corrosive effects.
In the field of lubrication, especially with the recent utilization of machinery and equipment within the high temperature environments of aerospace operations, it has been suggested the perfluorinated polyether fluids make excellent vehicles for lubricant greases. These fluids, when properly thickened to a grease consistency by conventional thickening agents, exhibit a high degree of thermal stability. This stability renders the greases especially suitable for use in lubricating loaded bearings subject to the degradative effects of high temperature situations. However, perfluorinated polyether greases have not developed their full potential as lubricants for high temperature operations because of their inherent corrosiveness toward ferrous metals. This corrosiveness begins at about 550.degree.F, especially in contact over long periods of time. Previous attempts at overcoming the above problem have produced a number of corrosion inhibitors, but these are not effective over prolonged periods of use.
In accordance with this invention, however, it has been found that the addition of a silicone fluid to a perfluorinated polyether fluid reduces corrosion by the perfluorinated polyether fluid. This corrosion inhibition is exhibited whether the mixture has been thickened to a grease or is used in fluid form. It has also been found that the silicone fluid is effective as a corrosion inhibitor over prolonged periods of use.